The present shared instrument proposal requests funds to purchase a new state-of-the-art Hitachi transmission electron microscope to be utilized by seven PHS supported investigators to enhance the progress of their current research projects. As indicated in section 2a of the proposal, we have a single antiquated transmission electron microscope in our College and increased usage of this instrument over the past two years has generated heavy scheduling conflicts that have severely limited individual access to a transmission electron microscope. The acquisition of the proposed Hitachi scope would alleviate this problem and provide us with additional essential capabilities that we currently are lacking. Project Summaries: Dr. Beitz's projects involve the combined use of electron microscopic (EM) immunocytochemistry and neuronal tract tracing procedures to define the chemical circuitry of the cerebellar deep nuclei and the spinal trigeminal nucleus. Dr. Johnson's project also utilizes EM immunocytochemistry in combination with morphometric analysis to analyze the localization of a recently discovered islet amyloid polypeptide in beta cells of the pancreas from normal cats, from cats with impaired glucose tolerance and from cats with overt diabetes mellitus. Dr. Louis's work employs EM immunocytochemistry to localize a lens membrane protein to the junctional regions of the lens plasma membrane and to define the structural relationships of the muscle sarcoplasmic reticulum calcium release channel/ryanodine receptor protein. An important component of Dr. Larson's projects involves the use of anatomical double labeling procedures at the ultrastructural level to determine whether anterogradely labeled primary afferent terminals in the spinal cord contain glutamate-like immunoreactivity, whether these terminals are surrounded by astrocytic processes containing glutamate dehydrogenase or glutamine synthestase and whether glutamate immunoreactive terminals co-contain CGRP or substance P. Drs. Madl, O'Grady and Brady also utilize, or plan to utilize, EM immunocytochemistry in their work. Dr. Madl's project requires the immunocytochemical localization of amino acids in axon terminals of neurons subjected to hypoxic conditions while Dr. O'Grady's work involves the ultrastructural localization of a novel cardiac antisecretory peptide in the heart, small intestine and gallbladder. Dr. Brady plans to use novel monoclonal antibodies against carnitine acyltransferases to analyze the location of these enzymes in the mitochondria and peroxisomes of liver cells.